Patent GB-190301855-A (GB)
Title: Improvements in Wireless Telegraphy
Inventor: JUSTICE PHILIP MIDDLETON
Filed: 1903-01-26
Granted: 1904-02-26
Abstract: 1855. Justice, P. M., [Hogg, W. S.]. Jan. 26, Telegraphs.-A system of syntonic wireless telegraphy is described, in which two or more differently-tuned receiving-arrangements are employed. The circuits of the two rods are tuned to different values, and the coherers or their equivalents are arranged in a common circuit with choking-coils, so that the receiver is only actuated when signals are received by both rods simultaneously. Fig. 2 shows one arrangement when two aÙrial rods a are employed. b, b<1> are inductance "tuners," and d, d<0> are intensifiers. The Figure shows the circuits set for receiving, the switches c<1>x, c<2>x being turned to connect up the oscillator when it is desired to transmit. Each coherer f<1>, f<2> is connected to its aerial rod through two intensifiers d, d<0>, two tuners b, b<1>, and an adjustable self-inductive resistance. The coherer local circuit includes choking-coils j<1>, j<2>, a battery, and a receiver or relay. In a modified form, the second tuner and intensifier are omitted from each side, but two adjustable self-inductive resistances are employed, one between the intensifier and its coherer and the other between the intensifier and the earth. Three other modifications, in which only a single aÙrial wire is shown, consist in closing the coherer circuit by two opposite side plates of the intensifier, connecting the intensifier and coherer to earth through self-inductive resistances, or insulating one end of the intensifier. One form of the tuner is shown in Fig. 6, in which b<2> is a brass tube mounted on a glass or other insulating tube b<3>, and having its central portion cut to form a spiral. The tube b<3> is mounted in insulating- supports b<4>. An iron rod b<9>, mounted in a glass tube b<10>, can be moved in and out of the tube b<3>. A spring sliding contact b<6> is mounted in a metal frame b<5>, which is supported at one end b<14> in contact with the brass tube b<2> and at the other end b<13> is insulated from or by the glass tube b<3>. In a modified form of the outer spirally-cut tube, the pitch of the cut is stated to be 4 inches, and there are plug sockets in which plugs can be placed to connect adjacent coils. An inner tube is also employed, which may be continuous or cut in a close spiral of one inch pitch, and is arranged to slide, a rod, screwed into one end, acting as an index and being supported on a bracket working with guides. The intensifier consists of a sheet of tin foil coated on each side with paraffined paper and closely folded into a zig.zag d', Fig. 9. The zig-zag is mounted in a wooden box d<3>, and has the ends bared so as to press against metal plates d' to which terminals d<5> are attached. The box is made solid with paraffin, and two metal plates d' are placed close to the folded faces of the zigzag. A self-inductive resistance is formed by cutting right and left handed screw-threads on an insulating-rod, so that the threads meet at the centre and that a resistance wire laid in the threads lies well in the groove. The rod is rotatably mounted in a case, and has an index and operating-handle on one end. The case has a dial adjacent to the index, and has one face slotted and graduated. Two blocks, carrying spring contacts engaging with the thread and the wire, are mounted to slide in the slotted face. Two rods with wires may be mounted parallel in one case. and may be geared together so as to he adjusted simultaneously.